Tag: iphone x

Troubleshooting iPhone X Won’t Turn On – Expert Repair Guide
Our previous blog has walked you through the work-flow of iPhone X Boot Circuit .

And you have learned that to have the phone turned on, working conditions like power supply, clock signal and reset signal are indispensable.

Since there are so many components involved in the process, reasons for won’t turn on of the phone can also be various.

Today we will explain the troubleshooting and repairing process of iPhone X by showing a real-life iPhone X won’t turn on case.

Follow our repair guide step and step and you can definitely learn something.

Analyzing

First, run cosmetic inspection of the motherboard.

The motherboard is not deformed or water damaged.

Then connect the motherboard with the DC power supply.

We can see that there is no current leakage.

Judging by this, the three main power supply rails, PP_BATT_VCC, PP_VDD_MAIN and PP_VDD_BOOST are in normal condition.

Continue to get the motherboard booted up with tweezers.

We can see that the boot current is larger than normal value.

We can confirm now that the fault is probably related to the 17 power supply rails outputted from PMU.

Motherboard Separating

Now we need to separate the motherboard to confirm whether the fault is related to the upper layer or the lower layer.

Place the motherboard on the specialized Heating Platform.

With temperature of the platform reaching the set temperature, pick up the upper layer with tweezers carefully.

Continue to take the lower layer off the platform.

Diagnosis

Now we can test the upper layer.

Connect the battery connector on the upper player with the DC power supply.

Then get the upper layer booted up with tweezers.

The boot current is still larger than normal value.

We can confirm now that the fault is related to the upper layer.

So our next step is to check the 17 rails outputted from PMU one by one.Let’s start with PP_CPU_PCORE first. Locate C2701, one of the test points of PP_CPU_PCORE on Refox.

Then run diode mode measurement of a capacitor on C2701 relevant circuit.

The measured value is normal.

Continue measuring test points of the remaining 16 rails.

Judging by the measured value, PP3V0_NAND has shorted.

Since there are many components on PP3V0_NAND, we can locate the faulty component with rosin detecting.Dip some rosin with the Soldering Iron at 350℃.

Then smoke rosin on components on PP3V0_NAND.

Set the output voltage of the DC Power Supply at 3V. Get the black probe grounded.

Meanwhile, get the red probe touched with a capacitor on PP3V0_NAND.

We can see that rosin on C2649 melts immediately.

Judging by this, C2649 has been damaged.

Troubleshooting

Let’s try to detach C2649 from the board and see how it works.

Remove black adhesive around C2649 first.

Then we can just remove it with tweezers slightly.

Again, get the red probe grounded.

Touch the two pins of C2649 with the black probe.

The measured value is normal.

We can confirm now that the shorted condition is caused by damage of C2649.

Still, we need to test the upper layer.

Remove the upper layer and clean with PCB Cleaner.

Connect the battery connector on the upper layer with the DC Power Supply.

Get the upper layer booted up with tweezers.

The boot current is normal this time.

Motherboard Recombining

Next thing we need to do is to solder the two layers together.

Remove heat insulation adhesive on the lower layer first.

Then place the lower layer onto the heating platform.

Power on the heating platform and apply some Paste Flux to the third space PCB.

Then get the upper layer in position.

Reassemble And Test

Get the display assembly installed.

Connect the battery connector with the DC Power Supply and get the motherboard booted up with tweezers.

The boot current is normal.

The phone comes with normal display and can get access to the system. Fault cleared.

Tools Used
Free Schematic Software: Refox

Visit our online shop for more parts and tools.

You can also visit REWA YouTube Channel to check our video and learn how to repair the iPhone X step by step.

[uploading100%] When repairing iPhone logic boards, we identify the issue first, find out why it occurred next, and figure out how to fix it in the end.

This is a general process adopted by professional repair technicians around the world.

Wanna be a professional repair technician and handle iPhone tough repair?

You need systematic training courses on REWA Academy .

Just click the course link below to know more!
December 7, 2023
How to Fix an iPhone X Won’t Charge: A Comprehensive Repair Guide
When your iPhone X won’t charge, it can be a frustrating experience, especially after multiple unsuccessful repair attempts. In this guide, we’ll walk you through a detailed troubleshooting and repair process to resolve charging issues, focusing on cases where the phone has already been worked on by other technicians.

Phone Details:

Model: iPhone X

Announced: 2017, September 12

Defect Phenomenon

The iPhone X was brought in with a non-functional charging port, and despite being repaired by several shops, the problem persisted. There was no charging symbol when connected to a charger, and tests using a USB multimeter charger detector showed no charging current.

Troubleshooting the Charging Issue

1: Initial Inspection

After disassembling the phone and inspecting the motherboard, it was clear that the board was dirty and oily, with excess flux paste visible. This was an immediate red flag, as improper handling and poor-quality repairs can lead to further complications.

2: Diode Value Check

The next step was to measure the diode values on the battery connector. Fortunately, all the diode values were within the expected range, indicating that the issue wasn’t with the basic battery circuitry.

3: Motherboard Separation

Given the state of the motherboard, we decided to separate the two layers for a closer inspection. Placing the board on a heating platform allowed us to separate the layers, revealing a messy interior full of low-quality solder paste flux. Additionally, the charging circuit components had been poorly resoldered by previous technicians.

Repair Process

1: Cleaning the Motherboard

The first and crucial step was to thoroughly clean the motherboard using a PCB cleaner. This not only removed the excess flux and dirt but also allowed for a more accurate assessment of the board’s condition.

2: Replacing the USB IC

Based on our repair experience, the USB IC often has a high failure rate and is a common culprit in charging issues. Here’s how we replaced it:
- Remove the Original USB IC: Carefully desolder the existing USB IC using a hot air gun.
- Prepare the PCB: Apply solder paste flux to the area and clean the PCB with solder wick and a soldering iron to remove any residual tin.
- Install the New USB IC: Align the new USB IC in the correct position and use a hot air gun to solder it securely onto the motherboard.
3: Testing the Repair

After allowing the motherboard to cool down, we temporarily assembled the phone and connected it to a DC power supply. The good news? The phone charged normally, indicating that the repair was successful.

4: Recombining the Motherboard

The next step was to recombine the two layers of the motherboard using the heating platform. Once reassembled, we tested the phone again, and all functions, including charging, were working perfectly.

Tips for Technicians
- Keep It Clean: Maintaining a clean motherboard is not just a best practice but a sign of respect for your customers. Always clean off excess glue, solder paste flux, and other residues after repairs.
- Attention to Detail: Reapply any stickers and foam that were removed during the repair process. If possible, solder back the shielding covers to protect the components.
- Quality Matters: Using high-quality materials and tools is essential to ensure the longevity and reliability of your repairs.
Conclusion

The iPhone X charging issue was resolved by identifying and replacing a faulty USB IC, along with thoroughly cleaning and reassembling the motherboard. This guide highlights the importance of proper repair techniques and attention to detail, ensuring that the phone is returned to the customer in optimal condition.

If you’re facing a similar issue or have any questions about iPhone repairs, feel free to reach out or leave a comment below!
July 16, 2022
iPhone X Battery Replacement – Complete Guide

If your phone battery is in a low health condition, like 80%, it’s time to replace a new one. We will bring you a full case of iPhone X battery replacement as a reference.

All you need is a repair kit and a new battery. The repair kit should be included as below: tweezers, screwdrivers, pry piece, suction cup, heating pad, spudger, battery adhesive, and waterproof adhesive.

Firstly, please long press the phone to turn it off. Then you can use a pentagon screwdriver to unscrew the screws at the bottom of the phone.

Please pay attention to putting the screws aside well. You can place the screen face down on the pad for about 2-3 minutes after the heating pad is up to the temperature of 70—80°c.

And fix the suction cup at the bottom of the phone, lift the screen gently, and insert a pry piece underneath. Gradually move around the edge of the display, separating the screen along the gap.

The display assembly is still connected to the iPhone by cables, so don’t try to remove it completely. Again, please pay attention to the position of the cable to avoid damage.

The angle should not be greater than 90 degrees to prevent breaking the flex cable. The process of removing the cover is done.

Next, use a Tri-wing screwdriver to unscrew the screws on the shielding cover of the cable connector. You can use a spudger slightly to extricate the battery and the connector between the screen and the motherboard.

Now, continue to follow instructions step by step. Detach the earpiece speaker flex cable, and remove the old display assembly.

Then, please use tweezers to clean up the battery adhesive. It’s suggested to detach the Taptic Engine and loudspeaker better to remove the adhesive at the bottom of the battery.

Again, use a Tri-wing screwdriver to unscrew the screws on the speaker flex cable and detach the shielding cover.

After taking out the loudspeaker and Taptic Engine, let’s continuously remove the battery adhesive. Because the adhesive at the bottom of the battery has been for a long time, it’s hard to remove it. We need to drop some alcohol to help clean up.

Drop the alcohol around the edge of the battery, and leave it to penetrate and evaporate. Use tweezers to make it loose, take out the old battery, and continue to remove the rest adhesive.

Please keep removing the waterproof adhesive around the frame. And replace the Taptic Engine and loudspeaker. Remember to tighten the screws and replace them with the new battery.

Tear off the film of the battery adhesive, and make its glue adhere to the battery. Press it slightly, and tear off the film. Please put on the new battery, and press it slightly.

Use a spudger to disengage the battery connector. Reassemble the display cable, touch the cable, and continuously.

Please turn it on. Check the health condition of the battery. It shows the maximum capacity of the battery now is 100%. Please turn it off. Tear off the waterproof adhesive. Make it adhere to the phone body. Press lightly with tweezers to make it adhesive.

Tear off the film. Reassemble the display cable and touch the cable. Reassemble the earpiece speaker flex cable, and connect the battery. Install the shielding cover, and tighten the screws.

Take off the waterproof adhesive around the frame. Buckle the phone screen.

Please turn it on again. Let’s do some battery tests. First is the wired charging test. Next is the wireless charging test. It’s working. Both are working.

The above guidance is about the battery replacement process. If you have any problems or advice, please leave us a comment below.

April 29, 2022
How to Replace iPhone X Screen Display

If you’ve broken your phone screen, here are some tips for display replacement. We will bring you a case iPhone X as a reference. All you need is a repair kit and a new screen. The repair kit should be included as below: tweezers, screwdrivers, pry piece, suction cup, heating pad, programmer, spudger, battery adhesive, and waterproof adhesive.

Before the screen assembly replacement, we need to check out the True Tone display function and whether it still works as usual or not to make sure the new screen will be working.

Firstly, please long press the phone to turn it off. Then you can use a pentagon screwdriver to unscrew the screws at the bottom of the phone. Please pay attention to putting the screws aside well. You can place the screen face down on the pad for about 2-3 minutes after the heating pad is up to the temperature of 70—80°c. And fix the suction cup at the bottom of the phone, lift the screen gently, and insert a pry piece underneath. Gradually move around the edge of the display, separating the screen along the gap. The display assembly is still connected to the iPhone by cables, so don’t try to remove it completely. Again, please pay attention to the position of the cable to avoid damage. The angle should not be greater than 90 degrees to prevent breaking the flex cable. The process of removing the cover is done.

Next, use a Tri-wing screwdriver to unscrew the screws on the shielding cover of the cable connector. You can use a spudger slightly to extricate the battery and the connector between the screen and motherboard. Now, continue to follow instructions step by step. Detach the earpiece speaker flex cable, and remove the old display assembly.

In order to retain the True Tone function on the display as everything in the iPhone is paired to another screen, it’s suggested to make good use of a programmer. Fasten the old touch connector on the corresponding connector of the programmer, and start reading. After everything is done, take off the old screen assembly, connect the new one to the programmer, and start writing.

Please connect the new screen assembly to the programmer, start writing, then place the old screen assembly on the heating pad. You can use a Tri-wing screwdriver to unscrew the screws of the earpiece cable and take out the earpiece. Tear off the protector of the new screen assembly and reassemble the earpiece cable on the new screen assembly. Lastly, tighten the screws. Please pay attention to the position of the grounding chip. Finally, we come to the connection part. Please connect the display cable, touch cable, earpiece cable, and battery accordingly.

If there is something wrong with the repair process or assembly issue, it’s better to do some tests after replacing a new screen.

It is the same step as the beginning. Long press to turn it on to do some screen test first. We need to do several tests: 3D touch testing, True Tone testing, and light adjustment testing. If your phone shows, all is usually working. Then you can tear off the waterproof adhesive and make it adhere to the phone body. Press lightly with tweezers to make it adhesive, tear off the film, reassemble the display cable, and touch the cable. And the earpiece assembly, and connect the battery. Install the shielding cover, and tighten the screws. Take off the waterproof film around the frame. Buckle the phone screen, and tighten the screws at the bottom.

Those are all iPhone X screen replacement steps we share with you. If there is any confusion, please leave us your comment.

April 23, 2022
Unlock NAND Data for NAND Repair – Fix iPhone X Stuck in Recovery Mode

Today we will share how to fix an iPhone X that is stuck on recovery mode.

Press the power button and the phone is stuck on recovery mode. Then we try to flash the phone. Open 3uTools to flash. The progress bar of flashing appears on the phone and the flashing gets stuck at 20%. An error also appears.

Getting stuck at different progress bar can initially tell us the corresponding repair solution. 11 % with an error and failure to enter recovery mode from DFU indicate that the CPU malfunctions. 13 % with an error means that the connecting port is faulty while 20% with an error always come with a NAND fault. So it can be preliminarily judged that the NAND fault has caused the problem.

Then we disassemble the phone. Remove foam on the motherboard. Wrap high-temperature tape around the motherboard.

Attach the motherboard to the holder. Heat with Hot Air Gun at 260 °C to remove adhesive around the NAND. Then heat the NAND evenly at 380 °C. Remove the NAND with a Pry Blade.

Apply some Paste Flux to the bonding pads. Apply some middle-temperature Solder Paste to the bonding pads with Soldering Iron at 360 °C. This is to neutralize the temperature of the bonding pads.

Clean the bonding pads with Solder Wick. Remove residual black adhesive with Hot Air Gun at 280 °C.

Clean the bonding pads with PCB Cleaner. Apply some Paste Flux. Put a known-good NAND in position.

Heat with Hot Air Gun at 340 °C. Push the NAND gently with Tweezers. When the NAND automatically resets, soldering is complete.

Tear off high-temperature tape. Connect the motherboard with a Power Cable. Measure the current of the motherboard. The current is 52 mA, which is normal.

Connect the phone with computer to keep flashing. The phone is successfully flashed. The not turning on issue is now confirmed to be caused by the NAND fault.

Turn on the phone for testing. Since WiFi and Bluetooth addresses are stored on the NAND, and the new NAND doesn’t match the WiFi and Bluetooth addresses on the motherboard, we need to read the data of the original NAND. In the first place, jailbreak the phone.

After jailbreaking, connect the phone with computer and open 3uTools. Open the software to read the original data.

Then we use P10 to write the data. Connect the phone to P10. Get the phone into DFU mode.

Open the P10 software. Click “DFU Mode”. After entering purple mode, the data have been successfully read and written.

The phone turns on normally. WiFi also functions well. The fault has been cleared.

October 9, 2021
Mastering Desoldering & Soldering of iPhone X PMU

Today’s handwork course will focus on a tutorial for desoldering and soldering the iPhone X PMU. Begin by attaching the upper layer of the motherboard to the PCB Holder, then proceed to apply High-temperature Tape on the surrounding components.

Start by removing the black adhesive surrounding the PMU. Apply heat using a Hot Air Gun set at 280℃ with an air flow of 3. Then, use a specialized knife to get rid of the black adhesive around the chip.

Caution: When removing the black adhesive near the PMU to prevent dislodging any nearby components.

Apply heat to the PMU using a Hot Air Gun set at 330℃ with an air flow of 5. Prior to heating, secure one end of the tweezers. After 15 seconds, when the solder begins to melt, swiftly lift the chip using the other end of the tweezers. Ensure that you lift the chip at the appropriate moment to avoid causing damage to the bonding pad.

Next, let’s clean the bonding pad. Apply some mid-temperature Solder Paste to the bonding pad. Heat with Hot Air Gun at 280℃. Meantime, clean the bonding pad with Soldering Iron at 360℃. Continue to clean the bonding pad with rosin soaked Solder Wick. Clean with PCB Cleaner afterwards. Tips: bonding pads of those empty pins might get knocked off the board when cleaning the bonding pad, which is normal. We can just leave them alone.

Continue to remove black adhesive on/around the bonding pad. Also when we pry up the chip, components around get knocked off the board. So our next move is to re-solder these components. First, apply some Paste Flux to their bonding pads. Then, apply solders with Soldering Iron. Get these components in position. And then solder with Hot Air Gun at 330℃, air flow 3.

Before soldering the chip, clean the bonding pad again. Clean with PCB Cleaner afterwards.

Also when we remove the black adhesive, some of the insulation varnish on PCB has fallen off the board. So we need to remedy with the UV Curable Solder Mask. Dip some UV Curable Solder Mask with tweezers. And apply the solder mask to the exposed area. Then, solidify with the UV Dryer Lamp for 5 minutes.

Now we can solder the PMU. Apply some Paste Flux to the bonding pad. Get a new PMU in position. Make sure you put it in the right direction. Solder with Hot Air Gun at 330℃, air flow 3 for 20s.

With the chip sinking and Paste Flux flowing, continue heating for 10s. Wait for the upper layer to cool for 5 minutes. Tear off the High Temperature Tape. Clean with PCB Cleaner afterwards. iPhone X PMU soldering and desoldering completed successfully.

September 17, 2021
iPhone 8/X Light Sensor Failed Even With Genuine Parts Repaired By Third Party

Recently, REWA has got feedback from a number of third-party repair shops that some iPhone 8 series and iPhone X have got “ambient light sensor not working issue” after repairing even with genuine parts. After testing and analysis, REWA LAB has found that Apple might have set up some technical barriers for repairing to prevent customers from resorting to third-party repair.Let’s check the video and find out the testing procedures and results.

September 8, 2021
iPhone X Unresponsive Touch Screen Repair

Our course today is about iPhone X touchscreen unresponsive repair.

Press the power button to turn on the phone. The phone turns on normally. Touch screen of the phone is unresponsive.

Turn off the phone and take apart it. Disconnect the battery and remove the display assembly.

Take out the motherboard. The first thing we do is to check the Touch ID FPC connector J5800. Run diode mode measurement of J5800. The measured value of Pin 22 is OL which indicates that Pin 22 relevant circuit has open-circuited.

We can see that there is an inductor FL5893 on the circuit. Let’s start with FL5893.

First, remove sponge around J5800 with tweezers. Run diode mode measurement of Pin 1 and Pin 2 of FL5893. The measured value of the two pins is 0. Judging by the measured value, FL5893 is in normal status.

We can see that the circuit makes its way to the third space PCB. So we need to separate the motherboard to check the third space PCB. Place the motherboard on the specialized Heating Platform. With temperature of the platform reaching 160℃, pick up the upper layer with tweezers.

As you can see, plenty of solder joints on the third space PCB have fallen off. And the motherboard is severely deformed. Judging by this, the motherboard is unrepairable.

Conclusion

iPhone X touchscreen is unresponsive. The first thing we do is to check the Touch ID FPC connector J5800. Run diode mode measurement of J5800. Judging by the measured value, Pin 22 relevant circuit has open-circuited. We can see on the bitmap that the circuit makes its way to the third space PCB. Separate the motherboard and we find that plenty of solder joints on the third space PCB have fallen off. The motherboard is also severely deformed. Judging by this, the motherboard is unrepairable.

September 1, 2021
How to Fix iPhone X Bottom Speaker Not Working

Today we will share how to fix iPhone X bottom speaker not working.

The phone features a broken screen and a deformed housing. Get a new display assembly installed and test. The phone turns on normally. Both the front camera and the rear camera work normally. WiFi also functions well.

Go to Sounds & Haptics > Ringtone. Select a default ringtone and there is no output sound. But the sound works fine with headphones in.

The preliminary judgment is that the audio circuit is in normal condition. It’s just that the bottom speaker is not working. Remove the display assembly and disconnect the battery. Disconnect the charging port flex cable. Run diode mode measurement of Pin 1 and Pin 45 of the DOCK connector. The measured value is 5, which indicates that the bottom speaker is in normal condition.

Continue to measure Pin 1 and Pin 45 of the motherboard connector J6400. The measured value of Pin 45 is 602, which is normal.

The measured value of Pin 1 is OL, which is abnormal.

Judging by this, Pin 1 relevant circuit has been open-circuited. Pin 1 of J6400 is connected to Pin 2 of the speaker amplifier IC U4900 by way of Pin S162 on cylinders around the edge of the lower layer. So our next move is to check the circuit carefully. Disconnect flex cables on the motherboard and take out the motherboard. Fix the motherboard to the Holder. Heat with Hot Air Gun at 360℃, air flow 65.

One minute later, pry up the upper layer step by step. Tips: make sure you pry up the upper layer at the right moment when tins on cylinders have melted. We can see clearly that there are multiple missing pins on the upper layer, including Pin S166 of the NFC circuit.

Judging by this, the phone has been dropped, which resulted in pseudo soldering of the motherboard accompanied with the detachment of pins. Since most of those missing pins are ground pins, we can just ignore them. Yet we need to treat Pin S166 with jumper wiring. Remove tins on cylinders around the edge of the lower layer and bonding pads of the upper layer with rosin soaked Solder Wick. Clean with PCB Cleaner afterwards.

Run diode mode measurement of Pin S162 on cylinders. The measured value is 570, which is normal. Continue to measure Pin S163. The measured value is 570, which is normal. Judging by this, the open-circuited condition of Pin 1 relevant circuit is caused by pseudo soldering of cylinders around the edge of the lower layer.

Now, let’s get the motherboard installed to the testing kit. Buckle up the extension flex cable of the display assembly. Then the charging port flex cable and the display assembly. Connect the battery connector with the DC Power Supply. Short Pin 9 of J4300 to the ground with tweezers. The system will then detect power button press. Current reading on the ammeter is normal.

Go to Settings > Sounds & Haptics > Ringtone. Select a default ringtone. Normal output sound this time.

We can confirm now that the upper layer and the lower layer are normal. And the fault is caused by pseudo soldering of cylinders. We can fix the problem by soldering the two layers together. Also before soldering, we need to treat Pin S166 with jumper wiring. Apply tins to the Via with Soldering Iron at 360℃. Prepare a length of tin applied Enameled Copper Wire of 0.02mm in diameter. Solder one end to the tin applied Via.

Clean with PCB Cleaner afterwards. Then apply some UV Curable Solder Mask to the soldered area. And solidify the upper layer under UV Dryer Lamp for 2 minutes.

Then get the other end to the right position. Next, attach the lower layer to PCB Holder. Fix the BGA Reballing Stencil to the right position. Smear Soldering Paste evenly on the BGA reballing stencil with BGA Scraper. Wipe out excess Soldering Paste with lint-free wiping cloth.

Then heat evenly with Hot Air Gun at 350℃, air flow 35. So that all solder balls can solidify completely. Remove the BGA reballing stencil after 2 minutes. Heat again with Hot Air Gun to ensure the formation of solder balls.

Apply some BGA Paste Flux to cylinders around the edge and get the upper layer in position.

Heat evenly with Hot Air Gun at 350℃, air flow 65. The soldering process is finished with the upper layer sinking and Paste Flux overflowing.

Wait for the motherboard to cool for 5 minutes. Now, let’s assemble the phone and test. Go to Settings>Sounds&Haptics>Ringtone. Select a default ringtone, normal output sound this time.

September 1, 2021
How to Fix iPhone X Stuck On Apple Logo/iTunes Error 4014

Our repair course today is going to be about iPhone X Stuck On Apple Logo/iTunes Error 4014 troubleshooting.

Run cosmetic inspection of the motherboard first. The motherboard is not deformed or water damaged.

Let’s get the motherboard installed and check. The phone won’t turn on.

Connect the phone with computer and restore via iTunes. Error 4014 appears.

Judging by iTunes error codes and their corresponding analysis, the fault might be caused by damage of the NAND flash chip or malfunction of NAND relevant circuits. Let’s start with measurement of the power supply of NAND. Connect battery connector with the DC Power Supply. Get the motherboard powered on with tweezers.

Run voltage measurement of the power supply of NAND. The measured value (0.9V, 1.8V and 3.0V) is normal.

Let’s replace with a new NAND flash chip and see how it works. Place the motherboard on the specialized Heating Platform. Remove the sponge covering the board first. Power on the heating platform and set the temperature at 155℃.

With temperature of the platform reaching 155℃, pick up the upper layer with tweezers carefully. Tips: please be careful when separating the motherboard.

With solder balls on the third space PCB remaining the same, we can skip the reballing process when soldering the two layers back together. Attach the upper layer to the PCB Holder. Heat with Hot Air Gun at 280℃, air flow 3 to tear off the sticker. Continue heating to remove black adhesive around NAND.

Then heat with Hot Air Gun at 340℃, air flow 5. Pry up the NAND flash chip carefully.

Place the NAND flash chip on the staging area of the PCIE repair programmer. Click ‘Backup Kernal Data’ to backup data of the chip. These backup data will be saved in the computer.

Take out the NAND flash chip. Place the new NAND flash chip on the staging area. Click ‘Write Kernal Data’. Choose the data file saved in the computer. The software will write the backup data to the new chip.

Once finished, click ‘Query Info’. Basic info of the new chip will be displayed on the interface. Once done, take out the new NAND Flash chip. Now we need to get the new NAND flash chip reballed. Get the BGA Reballing Stencil in position. Smear medium-temp solder paste evenly on the stencil. Heat with Hot Air Gun at 300℃, air flow 3 So that all solder balls can shape up completely. Once completed, wait for 1 minute

Then separate the NAND flash chip from the stencil. Heat again to ensure the formation of solder balls. Let’s move on to NAND soldering. Before soldering, apply some medium-temp solder paste to the bonding pad with Soldering Iron at 365℃.

Clean the bonding pad afterwards. Then clean thoroughly with Solder Wick and clean with PCB Cleaner afterwards.

Continue to heat with Hot Air Gun at 300℃, air flow 3. Remove residual black adhesive on the bonding pad. Now we can apply paste flux to the bonding pad.

Get the new NAND flash chip in the right position. Solder with Hot Air Gun at 330℃, air flow 4.

Next thing we need to do is to solder the two layers together. Before soldering, we need to remove heat insulation adhesive on the lower layer. Then apply some Paste Flux to the third space PCB. Get the upper layer in position. Power on the heating platform. With temperature of the platform reaching 155℃, continue heating for 1 minute.

Power off the heating platform. Wait for the motherboard to cool for 5 minutes. Now we can assemble the phone and test. Connect the phone with the computer. Restore the phone via iTunes. The phone can be normally restored. Once completed, the phone turns on normally. We can see SN and IMEI number here. Since the motherboard is iCloud locked, the activation work can only be finished by its owner.

Conclusion

iPhone X iTunes error 4014. Judging by iTunes error codes and their corresponding analysis, the fault is likely to be related to NAND flash chip or relevant circuits of NAND. Let’s start with the power supply of NAND. The measured value is normal. Which indicates that the problem is probably related to the NAND flash chip. Try to replace it with a new chip and the problem is fixed.

If you want to study more iPhone repair knowledge, please visit REWA Academy.

August 10, 2021
Troubleshooting iPhone X Not Responding in Sleep Mode

Hello guys, today we will walk you through the troubleshooting of a rare case of iPhone X not responding in sleep mode when getting incoming calls.

Go to Settings>Sounds & Haptics. All going well.

With the screen on, place a call to the phone using a known-good phone. The decline and answer buttons appear on the screen.

Turn the screen off. Place a call to the phone using a known-good phone. The phone is not responding at all. Press the power button to turn the screen on. We can see the decline and answer buttons on the screen.

Judging by this, relevant circuits of the baseband wake signal might have malfunctioned. Take apart the phone and disconnect the battery. Remove the display assembly and take out the motherboard.

Attach the motherboard to the PCB Holder. Heat with Hot Air Gun at 200℃, air flow 3. Tear off the heat dissipation sticker on the backside of the motherboard.

Open the bitmap software. Locate BB_TO_PMU_PCIE_HOST_WAKE_L. Since relevant circuits of the wake signal might have malfunctioned, we can try to borrow the wake signal from WiFi relevant circuits.

Locate WLAN_TO_PMU_HOST_WAKE. We can connect PP101_E-1 (the test point of the baseband wake signal) with PP7611_W-1 (the test point of the WiFi wake signal) by jumping a wire.

Scrape off the insulating coating on the two test points first. Then apply some solder paste to the two bonding pads. Heat with Soldering Iron at 365℃. Tin the two bonding pads with solder paste.

Connect PP101_E-1 to PP7611_W-1 with 0.02mm Enameled Copper Wire.

Then coat the wire with the UV Curable Solder Mask.

Now we can assemble the phone and test. With the screen off, test again. All going well. Fault cleared.

August 4, 2021
iPhone X no Response after Entering Password

Today our repair course is about fixing an iPhone X that freezes after entering passcode.
The iPhone X freezes after entering passcode.

Based on our experience, the issue is probably related to the NFC circuit.

Take apart the phone and disconnect the battery.

Remove the display assembly. Take out the motherboard.

Run cosmetic inspection of the motherboard. The motherboard is not water damaged.

The first thing we do is to separate the upper layer from the lower layer.

Remove dust-proof sponge on the board. Set temperature of the heating platform at 160℃.

Place the motherboard on the heating platform.

With the temperature of the platform reaching 160℃, take down the upper layer with tweezers and then the lower layer. The upper layer and the lower layer look just fine.

For further confirmation, let’s test the two layers with the test fixture. Before test, we need to clean the third space PCB. Attach the lower layer to the PCB Holder.

Heat with the Soldering Iron at 365℃. Clean pads around the edge of the lower layer with rosin soaked Solder Wick. Once done, continue to attach the upper layer to the PCB Holder.

Heat with the Soldering Iron at 365℃. Clean pads around the edge of the upper layer with rosin soaked Solder Wick. Clean with PCB Cleaner afterwards.

We find that S159 pad on the upper layer has come off the board.

S159 pad is the audio signal of the audio/speaker amplifier IC U5000.

Coming-off of the pad means that NFC connecting pads nearby might have been pseudo soldered and therefore resulted in the frozen screen issue.

Scrape with sculpture knife to get the circuit under S159 pad exposed. Then stick high temperature tape on components around.

Apply some mid-temperature solder paste to the missing pad.

Heat with Hot Air Gun at 300℃, air flow 2.

Once done, push the solder joint with tweezers carefully.

Make sure the solder joint has shaped-up perfectly.

Then remove a complete pad from a spare iPhone X motherboard.

Cover the pad face-down on the solder joint. Solder with Hot Air Gun at 300℃, air flow 2.

Tips: when soldering, press the pad gently with tweezers to ensure that the height of the pad is consistent with that of nearby pads.

Once done, apply some UV curable solder mask to the pad.

And then solidify under the UV Lamp for 10 minutes.

Continue to scrape with sculpture knife to get the pad exposed.

Clean with PCB Cleaner afterwards. Now we can test the upper layer and the lower layer with the test fixture. Attach the two layers to the test fixture.

Get the screen connected. Connect the battery connector with the DC Power Supply.

Get the motherboard powered on with tweezers. The phone turns on normally. Enter the passcode. The phone enters the home screen normally.

Touch function is also normal. We can confirm now that the fault is caused by pseudo soldering of the third space PCB. We can fix the problem by soldering the two layers back together.

Put the lower layer into the reballing mold. Get the BGA Reballing Stencil in position.

Place the mold onto the base. The stencil is tightly attached to the lower layer because of the magnetic structure of the base. Smear some low-temp Solder Paste on the stencil.

Wipe off excess solder paste with lint-free wiper. Then take the mold down from the base. Remove the reballing stencil.

Heat the lower layer on the heating platform at 160℃.

Once solder balls have shaped up completely. Cool for 5 minutes. Apply some BGA Paste Flux to the third space PCB.

And get the upper layer in position.

Power on the heating platform. With the temperature reaching 160℃.

Turn the power switch off. Cool for 5 minutes.

Then take down the motherboard from the heating platform.

Again, let’s assemble the phone and test. Fault cleared.

July 15, 2021